Caging mechanism



Oct. 28, 1969 A. GILMARTlN} 3,474,688

CAGING MECHANISM Filed Jan. 5, 1967 2 Sheets-Sheet 1 I John A.Gilmariin, INVENTOR.

BY m wi w A T TQRN EY.

Oct. 28, 1969 J. A. GILMARTIN CAGING MECHANISM 2 Sheets-Sheet 2 Filed Jan. 5. 1967 Fig. 3.

John A. Gilmorfin,

INVENTOR.

ATTORNEY.

United States Patent O 3,474,688 CAGING MECHANISM John A. Gilmartin, Manhattan Beach, Calif., assignor to TRW Inc., Redondo Beach, Calif., a corporation of Ohio Filed Jan. 5, 1967, Ser. No. 607,431 Int. Cl. Gg 5/06; G01c 19/24 U.S. Cl. 74--527 5 Claims ABSTRACT OF THE DISCLOSURE A caging mechanism for positioning and locking a deployable boom for satellites is dislosed. The deployable boom is rotatable and has at one end a slot which is chamfered such that when a longitudinal bar, which is normal to the axis of rotation, engages the slot, the deployable boom will rotate to a predetermined position and be locked.

BACKGROUND OF THE INVENTION The prior art field to which this invention is applicable is in satellite gravity gradient stabilization systems utilizing a deployable boom. The typical prior art mechanism for caging damped booms comprises a simple locking device which held the boom in position during boost operation. Upon a given signal, the mechanism was unlocked. As far as is known, the boom could not be re-positioned and locked.

In the U.S. Patent to Chombard, No. 2,808,726, there is shown a device for resetting a gyroscope which utilizes a roller on an inclined surface. The roller is applied parallel to the gyroscope axis. However, the force application is spaced to one side of the rotational axis which imparts lateral side loads in addition to a moment about an axis normal to the axis of rotation.

An example of an antenna stabilizing apparatus is disclosed in the U.S. Patent to Cady, No. 2,745,098. In the U.S. Patent to Glenny et al., No. 2,960,874, there is disclosed a gyroscope centering and caging apparatus.

SUMMARY OF THE INVENTION One feature of this invention is the provision for a caging mechanism for rotatable structures which is adapted to prevent rotation, but when released will allow free rotation. When actuated, the caging mechanism will rotate the structure to a null position and hold the structure against rotation.

BRIEF DESCRIPTION OF THE DRAWING FIGURE 1 is an end view partially in cross section showing a portion of the caging mechanism with relationship to a boom package which is shown in various positions.

FIGURE 2 is a side view, with portions broken away, of a caging mechanism constructed according to this invention.

FIGURE 3 is a view similar to FIGURE 2 showing portions in cross section and,

FIGURE 4 is a view partially in cross section as viewed along lines 44 of FIGURE 2.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring to FIGURE 1, an end view of the caging mechanism is illustrated with the deployable boom package shown in the null position and two other positions shown in dotted lines. The boom package is indicated at 2 with booms 4 and 6 extending therefrom. When used in a satellite, boom package 2 will have booms 4 and 6 stored therein during the boost operation of the satellite. Booms 4 and 6 when extended are quite long. When the orbit position is reached, the booms are extended by any wellknown means into space such as described in the U.S. Patent to Swaim, No. 3,177,987. The boom package is then unlocked so as to be able to rotate. The booms serve the purpose of orienting themselves with respect to the earth by gravity. As an example, assuming that boom package 2 is in the horizontal position shown, to be properly oriented it would have to be in the position shown by dotted line 8. Accordingly, the boom package 2 would be allowed to rotate to the proper position. This procedure will be described in detail as this description proceeds.

With reference to FIGURE 2, the boom package 2 with boom 4 is shown in side position. A hysteresis damping rotor is located at 10. This rotor is supported within frame 12 at one end by wire 14. The other end is supported by wire 16 as shown in FIGURE 3. Damping is provided by any well-known means such as a magnetic hysteresis damping suspension system which by itself does not form a part of this invention. Supports 18, 20, 22 and 24 are provided to prevent large displacement normal to and parallel to the axis of rotation of rotor 10. These supports are spaced slightly radially from the rotor. The axis of rotation of the rotor passes through wires 14 and 16. Thus, rotor 10 is ordinarily free to rotate about its longitudinal axis as there is little torsional resistance provided by wires 14 and 16. A brace 26 is provided which rigidly interconnects rotor 10 and boom package 2. Thus, when rotor 10 rotates, boom package 2 will likewise rotate with total support provided by wires 14 and 16. As viewed in FIGURE 2, it can be seen that freedom of rotation exists, whereas when the caging mechanism is actuated, longitudinal bar member 28 will enter slot 30 and pin 48 in aperture 50 as seen in FIG- URE 3.

Located within housing 32 is a motor, which may be a conventional electric motor, which when actuated will rotate screw jack 34 which has a right-hand thread on one end and a left-hand thread on the other end. Translating pistons 36 and 38 are threadably mounted on screw jack 34. Pistons 36 and 38 are restrained from rotation so that when screw pack 34 is rotated, pistons 36 and 38 are either moved toward each other or away from each other depending on the direction of rotation of screw jack 34.

Referring to FIGURE 3, when screw jack 34 is actuated so as to move pistons 36 and 38 away from each other, piston 38 will contact lever 40 which is pivoted above pivot pin 42. This will cause longitudinal bar 28 (see FIGURE 1 and FIGURE 2) to be rotated about pin 42 in a clockwise direction so as to engage slot 30. Should boom package 2 be oifset as shown by line 8 in FIGURE 1, a torque will be generated on the boom package which will rotate the package toward the null position shown by solid lines in FIGURE 1. This torque is caused by the reaction between bar 28 and slot 30. This reaction occurs because slot 30, as shown in FIG. 1, is chamfered or beveled so that as bar 28 engages the edge portion of the slot, a torque will be exerted on boom package 2. For example, assuming that package 2 is in a position shown by dotted line 8, the right-hand portion of bar 28 will engage the upper right edge of slot 30 and the left portion of bar 28 will engage the lower left edge of slot 30. These two reactions Will cause the slot 30 to align itself with bar 28, thus bringing boom package 2 to the horizontal position as shown in FIG. 1.

Simultaneously with rotation of bar 28 into slot 30, piston 36 will contact lever 44 which is pivoted about pin 46. This will cause pin 48 to engage corresponding aperture 50 of boom package 2. This provides support for boom package 2 such that movement along the longitudinal axis is precluded. In this connection, the center of bar 28, slot 30 and aperture 50 all lie along the longitudinal rotational axis of rotor 10 and boom package 2.

Continued rotation of screw jack 34 will compress spring 54 (see FIGURE 3). After pin 48 has contacted aperture 50', end 56 of piston 36 will contact a third locking element 58 which is shown broken away. This lever is likewise pivoted about pivot 46 and as shown in FIG- URE 4 includes arms 60 and 62. After pin 48 is located within aperture 50 and as bar 28 is toward the end of slot 30, arms 60 and 62 will be in forceable contact with boom package 2 to provide further lateral support. Spring 66 is attached to lever 40 to bias the lever to its released position. Likewise, springs 68 and 70 bias levers 44 and 58 to an open position.

Assuming that the mechanism (which may form part of a satellite) is on the ground prior to boost operation, antenna booms 4 and 6 would be stored within package 2 and the locking mechanism would be in the position shown in FIGURE 3 so as to prevent rotation and movement of rotor and boom package 2. After the satellite has assumed the orbit position, the drive motor within housing 32, which may be an electric motor, will be activated so as to retract levers 58, 44 and 40 to the position shown in FIGURE 2. Assuming that the antena booms 4 and 6 were previously deployed, boom package 2 and damping rotor 10 will be rotated under the influence of the gravity oriented deployable booms to a position such as 8 or 9 in FIGURE 1, these being given only by way of example. Assuming that it is necessary to extend or retract the booms, screw jack 34 is activated in the reverse direction to engage the boom package as previously described. The boom package will return to its null position shown by solid lines in FIGURE 1. The booms 4 and 6 are then moved to another position with the boom package safely locked in position to prevent disturbance of the sensitive suspension wires 14 and 16. When the new position is reached, the caging mechanism unlocks as previously described, allowing boom package 2 and damping rotor 10 to rotate to a new gravity oriented position.

By providing a caging mechanism according to this invention, the delicate boom structure is protected during boom adjustment and during boost operation.

What is claimed is:

1. A rotatable structure adapted to rotate about a predetermined axis, said rotatable structure having a chamfered slot at one end thereof,

a caging mechanism for selectively locking, releasing and positioning said rotatable structure which comprises;

a locking element, said locking element including a longitudinal bar extending in a direction normal to said axis of rotation, said bar being adapted to engage said chamfered slot, on a line intersecting said axis, whereby said structure will rotate to a predetermined position and locked.

2. A rotatable structure according to claim 1 and further including a second locking element adapted to engage said structure at a point opposite said first locking element.

3. A rotatable structure according to claim 2 and further including a third locking element, said third locking element being adapted to engage said structure adjacent said second locking element when said structure is in its predetermined position.

4. A rotatable structure according to claim 2 wherein drive means are provided to draw said first and second locking means toward each other whereby to engage said structure at each end thereof.

5. A rotatable structure according to claim 4 wherein said second locking element engages said structure on a line intersecting said axis of rotation.

References Cited UNITED STATES PATENTS 2,808,726 10/1957 Chombard 745.1

2,884,787 5/1959 Simons 745.1

3,226,999 1/1966 Allison 74-527 MILTON KAUFMAN, Primary Examiner US. Cl. X.R. 

